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Re: [TCML] Tesla Coil Magnet Wire

Hi Matt,

The 10 VAC spec is in error.

See the data sheet for these resistors:

The maximum _continuous_ voltage for a resistor is a function of its power rating and resistance:

  V = Sqrt(P*R)

So, for a 100 watt 1k ohm resistor, the continuous voltage rating is about 316 volts.

For low duty cycles and short pulses, the maximum withstand voltage can be much larger. It depends on the construction of the resistor (resistance wire spacing and resistor length) and is typically up to 10X the max continuous voltage rating for a hollow-form ceramic wirewound resistor.

In a Terry filter, the maximum RMS current will be limited to the size of the NST bank - perhaps a 100-200 mA RMS, so the RMS voltage will only be 100-200 volts. They WILL get hot in use. If you have the option of ordering inductive or non-inductive style resistors, you may wish to specify inductive to help further block (and damp) VHF transients.

Bert Hickman
Stoneridge Engineering, LLC
World's source for "Captured Lightning" Lichtenberg Figure sculptures,
magnetically "shrunken" coins, and scarce/out of print technical books

Matthew Sweeney wrote:
On the Terry filter, I see these suggested:


But the specs say they are only good for 10VAC. I imagine the voltage seen
across these resistors will be much much higher than that - or am I missing

I found a few 200Watt 1KOHM ohmite resistors at ax-man for a few bucks a
piece but they are shorter than the above linked model, and apparently
rated at 1800V.

I'll be working on the coil form first, and during that time also the terry
filter. I don't intend to turn anything on until the filters are in place.
I found a 20A EMI filter at ax-man for $3 I think that's a decent price.



On Sun, Oct 25, 2015 at 4:09 AM, wt5y <wt5y@xxxxxxxxx> wrote:

I use a laminates and plastics 10" blade on my table saw for cutting HDPE,
would work for any cutting board. I found a one inch thick board of HDPE
Plastic I drilled the holes to fit 1/4" copper tubing then cut through them
with table saw to make them insulated supports for the primary coil.  Got
it from sears, sure you can find same blades at home depot, lowes, harbor
freight, etc.  It will have smaller teeth than a regular wood blade.  I
have used the Temco brand magnet wire from Amazon/Ebay on both my
secondarys.  The original was 26awg on 4" pvc.  The latest being 20awg on a
6" secondary form of pvc.

I used the same caps in my MMC .15UF 2000VDC.  but I used 16 In a string.
Started with 1 string.  Now I have 4 strings for a total of 64 caps.
Started with 12kv 30ma.  Then 12kv 30ma x 2.  Ended up with 12kv 60ma x 3
for 10ma total.with 64 caps.

Don't forget Terry filter.
John cooper

Sent from my Samsung GALAXY S5™, a Cricket 4G LTE smartphone

-------- Original message --------
From: Matthew Sweeney <msweeney23@xxxxxxxxx>
Date: 10/24/2015  21:05  (GMT-06:00)
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Subject: [TCML] Tesla Coil Magnet Wire

Hi all, I'm gathering supplies for my new small Tesla coil (4" x 20"
winding) and have a few quick questions.

I calculated to use 26AWG wire for this secondary, I've heard it is best to
use 22AWG or larger but I believe that is only for larger coils correct?

I found some affordable wire on Amazon:


This is 26AWG Polyurethane with a Polyamide over-coat. Does anyone have
experience with this manufacturer (TEMCo) or have suggestions on a more
reliable source? I'm willing to pay more for better quality but within
reason of course this is just a small coil.

I'm planning on using 13X0.15uf/2000V capacitors for about 10pf at 26KV
driven by a 12KV/30ma NST. Do you think that is sufficient voltage on the
MMC? I'll be using an adjustable PowerStat 20A power transformer so I can
run at lower voltages at first.

I can add more capacitors (30 total) but then the capacitance drops too low
towards resonance and I don't want to destroy my NST =)

I am still in pre-build stage so any suggestions would be very welcome.

Oh also does anyone know the best way to cut cutting board for supports? I
figured a table saw is inappropriate I do have a small band-saw but I guess
I'd need a different blade for plastics vs wood?

I'm trying to source some thin-walled 4" PVC but no luck so far except
special order for 20' lengths at menards - that won't fit in my car =)

Thanks for any suggestions!

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